(a) Field of the Invention
The present invention relates to a liquid electrophotographic apparatus for forming a toner image on a photoconductive drum using a developing solution while transferring the formed toner image onto a transfer material, and more particularly to the electrophotographic apparatus suitable for a color proofing.
(b) Description of the Related Art
As a system for forming a colored toner image, there is one known in which four color toner images are formed on a photoconductive material for each color in accordance with the electrophotographic manner to sequentially overlap those toner images on a transfer sheet.
There is another system in which a four color toner image is formed on a transparent disposable photoconductive material to transfer it for each of those colors. Besides, there is also one in which a plurality of toner images are respectively overlapped on the photoconductive drum by dry development so as to transfer these toner images onto a transfer sheet.
Further, as a high quality laser printer adapted for forming a proof, there is one in which a plurality of toner images are respectively overlapped on a photoconductive drum made of an organic photocopier material, which is sensitive to the infrared region, in accordance with the liquid developing method, to transfer these toner images onto a transfer sheet.
However, according to the above-described system, in which the four color toner images are respectively sequentially overlapped onto the transfer sheet, since the transfer sheet is elongated during the transfer operation, it is difficult to obtain the registration of each color image (registration).
In addition, according to the system using the transparent disposable photoconductive material, each time the images are transferred, a new photoconductive material must be used resulting in a relatively expensive system.
Further, in the system using the dry-type development, because of the large size toner particles, it is difficult to obtain a high resolution (2000 dot/inch or above) color toner image which may be adapted for to proofing obtain a satisfactory proof.
Still further, in a system using a photoconductive drum formed of the above-described organic photoconductive material, since the material is likely to deteriorate due to the presence of a carrier solution (isoparaffin series solvent) of the developing solution, it cannot be used many times. Finally, there has been a problem in achieving a relatively short transfer time of the image information.
In view of the above-described circumstances, an object of the present invention is to allow the drum-shaped photoconductive material to be repeatedly used while obtaining a high quality color toner image.